src/test/run-pass/issue-27401-dropflag-reinit.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // ignore-pretty #27582
  12
  13 // Check that when a `let`-binding occurs in a loop, its associated
  14 // drop-flag is reinitialized (to indicate "needs-drop" at the end of
  15 // the owning variable's scope).
  16
  17 struct A<'a>(&'a mut i32);
  18
  19 impl<'a> Drop for A<'a> {
  20     fn drop(&mut self) {
  21         *self.0 += 1;
  22     }
  23 }
  24
  25 fn main() {
  26     let mut cnt = 0;
  27     for i in 0..2 {
  28         let a = A(&mut cnt);
  29         if i == 1 { // Note that
  30             break;  //  both this break
  31         }           //   and also
  32         drop(a);    //    this move of `a`
  33         // are necessary to expose the bug
  34     }
  35     assert_eq!(cnt, 2);
  36 }